Decomposition of Water by tJie Galvanic Batten-y. 85 



minute as they issue from the jet, and are confined in the vol- 

 tameter for the remaining fifty-five seconds^ the flame will, when 

 thrown on lime, give a light twelve times as large as one a quarter 

 of an inch in diameter, or nearly seven-eighths of an inch in 

 diameter. If the breadth of the hole in the key of the stopcock 

 be gAjth of the circumference of the key, and if the key make a 

 revolution in every two minutes, the stopcock, because it is 

 opened twice in each complete revolution of the key, will be 

 opened once in every minute for five seconds, and will be closed 

 for fifty-five seconds. Now by clockwork it is very easy to 

 make the key of the stopcock perform a revolution once in 

 every two minutes, and consequently to produce a lime light 

 seven-eighths of an inch in diameter for five seconds in every 

 minute. It is easy to make the motion of the key and the ratio 

 of the diameter of the hole to the circumference of the key such 

 that the stopcock will be opened once in two minutes for ten 

 seconds, and will be closed for a minute and fifty seconds. In 

 order to light the gases whenever the stopcock is opened, it is 

 necessary to have a small flame of gas or of a candle always at 

 the nozzle of the jet. A lime light of seven-eighths of an inch 

 in diameter would be seen at a far greater distance, particularly 

 in foggy weather and in snow-storms, than the light of a lamp ; 

 and is therefoi'e of the utmost importance in lighthouses. Had 

 there been such a light in the Bayley Lighthouse, the Victoria 

 would in all probability not have been lost. The expense or 

 trouble of such a light would not be very great, and would be 

 amply compensated by saving the lives of many every year. The 

 light might be used only in foggy weather or in snow-storms, 

 when a light capable of penetrating through a dense atmosphere 

 or a shower of snow would be required. On other occasions the 

 ordinary lights might be employed. The expense of an inter- 

 mittent lime light, such as I have described, would be the cost 

 of working a cast-iron battery containing four zinc plates, each 

 6 inches by 8, for sixteen or seventeen hours a day, and of a very 

 minute flame of common coal-gas for the same space of time, as 

 often as the light might be required. Surely such an expense 

 could not be very great. Should it be apprehended that the 

 action of the battery would not be sufficiently constant to give 

 the light required, then three large gas bags, each of which 

 would contain as much of the mixed gases as would be sufficient 

 to maintain a lime light three-fourths or seven-eighths of an 

 inch in diameter for half an hour, might be filled during the 

 day with the mixed gases by two or three small batteries. Then, 

 by means of the apparatus which I have devised for safely ap- 

 plying the mixed gases to the production of intense heat and 

 light, of a proper jet, a suitable adjustment of clockwork, and a 

 very small flame of coal-gas, the intermittent light may be kept 



